Please do NOT just post the error dialogue that pops up at the time of the error.
For example, posting JUST this
WILL NOT HELP:
Click OK on that error, and the go to VIEW and the ERROR LOG:
Post what is in there for answers.
As you can see from my example, the error log shows me that when editing my WL_NSW line in the NFRM, I entered in an incompatible value.
Cheers